Gasification of coal under pressure typically produces streams containing methane, carbon dioxide, carbonyl sulfide, hydrogen sulfide, plus small amounts of ethylene, ethane and other compounds. Usually, the concentration of ethane and ethylene is low (on the order of 1 to 2 volume percent) and cannot be easily separated by conventional methods. Because of their value it would be desirable to recover the ethane and ethylene. The concentration of ethane and ethylene can be increased by addition of aliphatic hydrocarbons into certain parts of the gasifier, yet even so one is still faced with their separation from a large amount of other gases. The present invention provides an improved method of recovering ethane and ethylene from gaseous mixtures.